Critical: exim

Issue Overview:

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. Because Exim operates as root in the log directory (owned by a non-root user), a symlink or hard link attack allows overwriting critical root-owned files anywhere on the filesystem. (CVE-2020-28007)

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. Because Exim operates as root in the spool directory (owned by a non-root user), an attacker can write to a /var/spool/exim4/input spool header file, in which a crafted recipient address can indirectly lead to command execution. (CVE-2020-28008)

Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow because get_stdinput allows unbounded reads that are accompanied by unbounded increases in a certain size variable. NOTE: exploitation may be impractical because of the execution time needed to overflow (multiple days). (CVE-2020-28009)

Exim 4 before 4.94.2 allows Out-of-bounds Write because the main function, while setuid root, copies the current working directory pathname into a buffer that is too small (on some common platforms). (CVE-2020-28010)

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S. This may cause privilege escalation from exim to root. (CVE-2020-28011)

Exim 4 before 4.94.2 allows Exposure of File Descriptor to Unintended Control Sphere because rda_interpret uses a privileged pipe that lacks a close-on-exec flag. (CVE-2020-28012)

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow because it mishandles “-F ‘.(’” on the command line, and thus may allow privilege escalation from any user to root. This occurs because of the interpretation of negative sizes in strncpy. (CVE-2020-28013)

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. The -oP option is available to the exim user, and allows a denial of service because root-owned files can be overwritten. (CVE-2020-28014)

Exim 4 before 4.94.2 has Improper Initialization that can lead to recursion-based stack consumption or other consequences. This occurs because use of certain getc functions is mishandled when a client uses BDAT instead of DATA. (CVE-2020-28019)

Exim 4 before 4.94.2 has Improper Restriction of Write Operations within the Bounds of a Memory Buffer. This occurs when processing name=value pairs within MAIL FROM and RCPT TO commands. (CVE-2020-28022)

Exim 4 before 4.94.2 allows Out-of-bounds Read. smtp_setup_msg may disclose sensitive information from process memory to an unauthenticated SMTP client. (CVE-2020-28023)

Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary commands, because smtp_ungetc was only intended to push back characters, but can actually push back non-character error codes such as EOF. (CVE-2020-28024)

Exim 4 before 4.94.2 allows Out-of-bounds Read because pdkim_finish_bodyhash does not validate the relationship between sig->bodyhash.len and b->bh.len; thus, a crafted DKIM-Signature header might lead to a leak of sensitive information from process memory. (CVE-2020-28025)

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters, relevant in non-default configurations that enable Delivery Status Notification (DSN). Certain uses of ORCPT= can place a newline into a spool header file, and indirectly allow unauthenticated remote attackers to execute arbitrary commands as root. (CVE-2020-28026)

Exim 4 before 4.94.2 has Execution with Unnecessary Privileges. By leveraging a delete_pid_file race condition, a local user can delete arbitrary files as root. This involves the -oP and -oPX options. (CVE-2021-27216)

Affected Packages:

exim

Issue Correction:
Run yum update exim to update your system.

New Packages:

i686:  
    exim-debuginfo-4.92-1.33.amzn1.i686  
    exim-greylist-4.92-1.33.amzn1.i686  
    exim-mysql-4.92-1.33.amzn1.i686  
    exim-4.92-1.33.amzn1.i686  
    exim-mon-4.92-1.33.amzn1.i686  
    exim-pgsql-4.92-1.33.amzn1.i686  
  
src:  
    exim-4.92-1.33.amzn1.src  
  
x86_64:  
    exim-4.92-1.33.amzn1.x86_64  
    exim-pgsql-4.92-1.33.amzn1.x86_64  
    exim-mon-4.92-1.33.amzn1.x86_64  
    exim-greylist-4.92-1.33.amzn1.x86_64  
    exim-debuginfo-4.92-1.33.amzn1.x86_64  
    exim-mysql-4.92-1.33.amzn1.x86_64  

Additional References

Red Hat: CVE-2020-28007, CVE-2020-28008, CVE-2020-28009, CVE-2020-28010, CVE-2020-28011, CVE-2020-28012, CVE-2020-28013, CVE-2020-28014, CVE-2020-28019, CVE-2020-28022, CVE-2020-28023, CVE-2020-28024, CVE-2020-28025, CVE-2020-28026, CVE-2021-27216

Mitre: CVE-2020-28007, CVE-2020-28008, CVE-2020-28009, CVE-2020-28010, CVE-2020-28011, CVE-2020-28012, CVE-2020-28013, CVE-2020-28014, CVE-2020-28019, CVE-2020-28022, CVE-2020-28023, CVE-2020-28024, CVE-2020-28025, CVE-2020-28026, CVE-2021-27216